The invention relates to a method for manufacturing an accordion filter insert in which an accordion filter pack is introduced into a mold and a space remaining thereafter in the mold is filled with a liquefied polymer material, which subsequently solidifies in order to provide a frame surrounding the accordion filter.
This method is described in DE 21 66 432 A1, in which the accordion filter insert is configured as a pocket filter. The edge of the filter medium that forms the pocket filter is embedded in the plastic filter frame in such a way that the edge of the filter medium projects out of the frame on all sides as a seal. The filter medium itself consists of a material that is penetrated by plastic as it intersects the frame.
The seal provided by the filter medium protruding from the frame is unsatisfactory in terms of its utilization characteristics. For example, when viewed in the peripheral direction, the seal rests against the filter housing with different levels of preload. Relaxation phenomena can occur in the region of the seal during a long filter insert utilization period, resulting in leakages.
There remains a need to further develop this method such that it can be practiced more simply in terms of production engineering and with greater economy. A further need is that the filter insert manufactured by this method have improved utilization characteristics, particularly improved sealing of the frame surrounding the accordion filter pack against the filter housing. The preload of the frame should be of substantially uniform magnitude along its entire periphery, thus resulting in secure, rattle-free fixing of the accordion filter insert in the filter housing during a long utilization period.